1584 A Rare Case of Follicular Lymphoma of Sigmoid Colon

Abstract

INTRODUCTION: Follicular lymphoma is defined as a neoplasm of follicle B cells and is characterized immunohistochemically by a positive reaction to B-cell markers and Bcl-2. Follicular lymphomas of the colon are very rare. Within GI Lymphomas, colorectal lymphomas are very uncommon and account for only 3% of GI lymphomas and 0.3% of large intestinal malignancies. We describe an unusual presentation of extra-nodal follicular lymphoma within the sigmoid colon. CASE DESCRIPTION/METHODS: A 59-year-old Caucasian female with history of hypertension was referred by her primary care physician for an average risk screening colonoscopy. Prior to referral for screening colonoscopy, the patient was being screened for colon cancer with annual occult stool testing which had been negative. She underwent a colonoscopy which showed a sessile polyp in the hepatic flexure and two polypoid lesions in the sigmoid colon (Figure 1). The patient was referred for endoscopic mucosal resection of the polyps. A snare mucosal resection was performed for the hepatic flexure polyp (12 mm in size). The 2 sessile polyps in the sigmoid colon (8-12 mm in size) were also resected with a hot snare. Pathology from the sigmoid colon polyp was consistent with Grade IIIA Follicular Lymphoma and immunohistochemistry was positive for CD20, CD10, BCL6 and BCL2 (Figure 2). The polyp in the hepatic flexure was noted to be a benign sessile serrated polyp. Patient was referred to Oncology for further management. A bone marrow biopsy and PET/CT did not show any evidence of disease involvement elsewhere. DISCUSSION: Primary NHLs of the GI tract are rare, accounting for only 1 to 4 percent of malignancies arising in the stomach, small intestine, or colon. Colonoscopy with biopsy is the principal diagnostic modality. Colonoscopic findings of follicular lymphomas include mucosal ulcerations, diffuse mucosal nodularity or polypoid mass like lesions. However, due to its rarity, an optimal diagnostic work up and treatment plan has not been well established. Making a correct diagnosis of the disease based on findings of biopsied samples can be challenging and multiple biopsies or endoscopic mucosal resection may be required in addition to appropriate consultation with pathologists.